Have you ever wondered if there are things that contractors like to keep as professional secrets? Even the most honest, hardworking contractor has insider knowledge that you might not see from the consumer-homeowner side of things.

While you certainly want a contractor you can trust to tell you what you need to know, these insider tips are a gift from us as you go about bathroom remodeling upgrades. Your contractor may be upfront about everything—but we doubt they will tell you this.

Check out these seven things your bathroom contractor probably won’t tell you. And for help finding a good contractor, click here.

1. You don’t need me for every detail.

Some contractors like to finish their own job to completion, even if this means that the details get dissolved into their overall fee. Consider saving yourself money and time with the contractor in your house by completing smaller tasks, such as installing hardware, replacing doorknobs, and hanging mirrors, for a weekend DIY project.

2. Don’t tear down walls unless you have to.

Contractors are often amenable to changes if they are compensated accordingly. But we suggest that once you start a project, don’t make major changes. This can end up costing you much more than necessary. Come to the project with a complete plan, and leave room for only minor adjustments, not major changes of direction.

3. A bathroom-specific contractor is best.

While some contractors claim to be jacks-of-all-trades, a specific bathroom contractor is best. You’ll get higher quality, more efficient work. Why would you go to a pedodontist for your root canal? Get specialized, quality care.

4. Always go with standard sizes.

If you’re replacing entire countertops and vanities in your bathroom, consider going with the standard industry size. Doing so can save you tons of money on a needless custom fit of granite, concrete, or other materials. Unless you have something very specific in mind requiring a custom fit into a particular space, go with standard sizes.

5. Order your granite countertops pre-finished.

If you’re changing the surface of your bathroom countertops, consider that while granite countertops look great, they’re one of the most expensive materials to replace in a bathroom. Prefinished granite slabs can be cut to standard sizes before they are imported, lowering the cost of a “custom job.”

6. If possible, choose slate.

While granite is prime, slate countertops offer natural beauty at a more reasonable price. A slate floor, for instance, gives a refined look while helping you stay in the budget. Now is the right time for slate—the American market price has dropped considerably: from around $12 per square foot to $3-4/sq ft.

7. Let me buy all the materials.

No matter who’s dealing with the installation of materials—from that huge clawfoot tub to that small drawer pull—have your contractor buy all the materials. You can save money perhaps if you buy that sink yourself and haul it home. But you’ll really save time, money and hassle by leaving everything to the pros. Not to mention that they can often get insider discounts unavailable to regular consumers.